QUANTIFICATION OF THE UNCERTAINTY IN THE EFFECT OF IRRADIATION ON CHARPY PROPERTIES

The provision of material property values for use in safety assessment s requires the use of statistical analysis techniques which can produc e, for the deterministic approach, best estimate and confidence limit values and, for the full probabilistic method, probability distributio ns. In this paper a description is given of a robust and efficient met hod of analysis for deriving probability distributions which reflect t he information in the data. As this novel approach adopts a Bayesian v iewpoint for the analysis, the main aspects of this will first be pres ented before moving on to giving the details of the method. In order t o illustrate the use of the various methods, results will be presented of an analysis of the effect of neutron irradiation dose on Charpy im pact energy curves. On the basis of this analysis a model is derived w ith which it is possible to predict the form of the Charpy curve at an y dose and for any probability level. Comparisons between the model pr edictions and the measured values are shown. (C) 1997 Elsevier Science S.A.